Preparation of supported aluminum chloride catalysts



Patented Dec. 14, 1948 PREPARATION SUPPORTED CHLORIDE CATALYSTS Walter:Hz R'upp, Mountainside; and Clarke" T.

Harding; Hillside,.Nz J assignorsto Standard Oil Development Company; acorporation of Delaware No: Drawing. Original application August 171943; SerialNo. 498,974. Divided-and this ap=-- plication May 20; 1944,Serial No. 536,642

, The, present. invention relates to a new and) improved combinationtype catalyst, comprising essentially. ananhydrous aluminum halideimpregnatedin .a sorptive carrier, and to the novel.

methodrof preparing the same.

Aluminum halideicat'alysts of the type known as Friedel-Crafts catalystshaveheretofore been employed as activating. agents for various types of]organic. reactions such as, for example, the alkylationof'isoparafinswith olefins, the nuclear alkylation of aromatics with alkyl'chlorides,aloohols'. or olefins, the isomerization of normal 'parafiihs toisoparaifins, andthe polymerization of olefins to form normally liquidolefins of higher molecular weight which upon hydrogenation are suitablefor use as. motor fuel constituents; Greatdifiiculty is experienced inthe handling. ofTcatalyst masses usedv in connection with'these varioustypes of organic condensation and isomerization reactions because of thetendency 'of the aluminum .chlorideito' becomehydrolized'upon'contacting moisture. The catalystmasses enjoy their highest efiiciencywhen the entire system is kept under substantially anhydrous conditions;

This is arelativelydifficult matter because-ofthe facttliatnot only mustthe aluminumchlorid'e or aluminum bromide be maintained inanhydrousicondition but'in the handling. ofthe'carriers'in whichthese'various aluminum halides are sorbed, atmospheric moisturetends to"be'sorbed therein'so'that at least a'portion' ofthe aluminum'halides,.upon'being impregnatedin such porous" carriers; tends to"hydrolize, thereby. causing" a wastage of the aluminum halide; In thepast;

the sorptive' carriers and the various a'luminum' halides'have' beenshipped inair-tight; moistureproof containers, but because'ofthe'scarcity of materials" such expensive containers are not always "readilyavailable:

A particularly effective aluminum halide composite-catalyst is preparedby impregnating aluminum chloride or'aluminumbromid'ein a sorptive= 2'precautions to prevent the aluminum chloride. or aluminum bromide fromtaking, up water It is an object of the present invention. to obviatethe necessity for resorting to the useofi expensive drying equipment forremovingiwater from sorptive carriers which are to be. impregnated withaluminum halides.- It. is a further object. of the invention toobviatethe necessity for. employing expensive moisture-proof containersfor thetransporting of said. carrier. materials. Itiswa furtherobjectoflthe invention to obviate the need for extensive handling andresultant powdering of highly friable carrier materials for catalysts oftheheretofore-mentioned type. It is a further object of the inventionto. mini mize the possibility of effectingstructuralchange in thesehighly porous carrier materials when they: arecalcinedun'der severeconditions, suchas freeingtitaniuni chloride when a partiallydehydrated. bauxite is contacted with the. hydrogen chloride and.aluminum chloride .in theprocess. Other objects' will be apparent upon afuller understand-- in of theinvention to be hereinafter described:

The present invention resides in the discovery that it..is unnecessaryto subject a partially dehydrated bauxite or other sorptivecarrier'materialsuch as, for example, the sorptive aluminas, to drasticcalcining ordrying treatment priorto impregnating that carrier with'thedesiredaluminum halide and chargingthe resultantcomposite catalyst massto a reactor. It has now been discovered that the water contained inthese various" types of sorptivemateri'als may be conveniently? removedtherefrom even thou'ghno special'precautionshave been taken toprevent'thesorptiont of atmospheric: water'thereinto if. thecarriermaterials are simply charged: to thereactor. in" which thecatalyst is" to: be employed" and a" streamof superheatedhydrocarbonvapors passed. therethrough for a relativelyqshort period of timeoruntil the amount of moisture has been re-' duced' to the desired.minimum. Usually the" amount of moisture is'reduced to something like-3% by Weightwrless' fthe porous carrier; The? remaining moisture in'thecarrier has been found to be relatively firmly-combined with the carriermaterial and upon impregnating'the carrier with aluminum chloride,for'example, no degradation of the aluminum chloride results. Thus, forexample; apartially dehydrated bauxite contain"- ingmore than 3 weightper centof water, usually" 400 F.', preferably between. about 250" Fland.

3 350 F., is then passed through the partially dehydrated bauxite for aperiod of about 1.5 to 3 hours.

A partially dehydrated bauxite 50- treated was found to have .a watercontent of about 3% by weight or less and did not contain any free oruncombined water that would serve as a free hydrolyzing agent uponimpregnating this treated carrier with aluminum chloride. The carrier sotreated is maintained at the above-indicated temperatures and vaporsofaluminum. chloride or of aluminum bromide are then passed through thecarrier mass for a sufficient length of time to give the desiredconcentration of catalyst in the carrier mass. For most of the reactionsheretofore mentioned in which such a; catalyst may be employed, thetotal amount of aluminum halide adsorbed on the carrier may rangebetween about 6% and 40% by weight, of the carrier. For a catalyst to beemployed in the vapor phase isomerization of 'normaljparafiins toisoparaffins, a concentration of free aluminum chloride in a partiallydehydrated bauxiteranging'from 3% to 12% is adequate at any one time. Incase the catalyst, is to be employed in the alkylation of isoparafiinswith olefins, the amount of aluminum chloride impregnated in the carriermay range as high as 50% by weight although the upper limit as to the'amount of aluminum halide impregnated depends oftentimes upon thespecific structural nature'a'nd porosity "of the specific carrieremployed.

' The-impregnation of the aluminum halide vapors 'into the partiallydehydrated carrier mass may be carried out in a number of ways. Thus forexample, solid aluminum chloride as obtained incommerce may be heated toa temperature of about 360 F. and the sublimed vapors passed through thecarrier mass; Molten aluminum,

chloride may have a carrier'gas such as nitrogen, carbon dioxide,hydrogen or some similar inert gaseous material, passed therethrough andthe resultant admixture of aluminum chloride vapors and. carrier gas maythen be introduced into,

butane. need not be purged from the carrier mass oncethe partiallydehydrated bauxite has become dehydrated to the extent herein indicated;

and furthermore, not only does the invention, contemplate using the,same medium for dryingthe carrier material as will be used as a feedstock in the reaction employing the final catalyst mass, but the samemedium, for example normalbutane, at substantially the same temperatureas maintained on the carrier material during the dehydrating process orat a temperature slightly lower, may be employed for use in impregnatingthat ,carrier material so dehydrated with the requisite amount ofaluminum chloride. Thus, for/example, if it is desired to prepare analuminum chloridepartially dehydrated bauxite catalyst mass for theisomerization of normal 4 butane, the partially dehydrated bauxite maybe dried at a temperature of from 310 F. to 320 F. by passing driednormal butane therethrough at that temperature. The normal butane maythen be employed as a .carrier'medium for vapors of aluminum chlorideand this admixture passed through the dried carrier material until from8% .to 12% of aluminum chloride is impregnated in the partiallydehydrated bauxite. The catalyst mass may then be employed in theisomerization of normal butane by passing vapors of normal butane atsubstantially the same temperature as was employed for the impregnationof the catalyst mass and as was employed for the dehydration, of thecatalyst carrier, together with in connection with the isomerizationreaction. It

is within the scope of the invention to employ any normal gaseous orvaporized parafiinic hydrocarbon or other type compound not decomposedor reacted on by the carrier or catalyst in substantially anhydrousformas the drying agent for preparing a suitable sorptive carriermaterial to be impregnated with the aluminum halide desired. Thus, forexample, the following are suitable for use in dehydrating sorptivecarriers in the manner heretofore described: methane; ethane, propane,butane, isobutane, normal pentane, isopentane, and the similar higherhomologues of the .parafiin series, Mixtures of two or more of thesecompounds may likewise be employed; also nitrogen, carbon dioxide,hydrogen and air in superheated and anhydrous form may be employed,although purging operations are ultimately necessary if this class ofsubstances is used.

u The dehydration of the carrier and impregnation of the dehydratedcarrier mass with alumi-,

num halide may be carried out under superatmospheric or atmosphericpressures but in general atmospheric pressure or the pressure underwhich the catalyst mass is to be employed is;

preferred. In dehydrating the sorptive carrier it is at times preferableto maintain a temperature of at least 50 higher onthe carrier materialthan the temperature subsequently maintained on the final catalyst masswhen employed for. activating the particular reaction. By operating inthis manner, the absence of free moisture dur ing the reaction isinsured if the feed stockis adequately pretreated to remove all tracesof moisture therefrom.

A preferred modification of the present proc: ess contemplates theintroduction of aluminum chloride vapors into the sorptive aluminas at atemperature below the boiling point and sublimation point of aluminumchloride, yet removing;

vapors of aluminum chloride from an aluminum chloride drum containingsolid aluminum chlo-' ride through the expedient of reducing the partialpressure of the aluminum chloride by introducing into the presenceof thesolid aluminum chloride, hydrocarbon vapors. Such a method Example IAbout 110 grams of 4 to 8 mesh partially dehydrated bauxite was chargedto a closed reaction vessel. This bauxite had the following compositionas received from the supplier:

Weight percent A1203 77. 8 S102 11.3 F6203 1. 8 T102 3. 5 Volatilecontent 3. 1 Residue 2. 5

In storing and handling this material, it picked up atmospheric moisturein an amount ranging between about 5% and 7%, having been exposed to theatmosphere for some period of time. A stream composed predominantly ofnormal butane was heated to a temperature varying between about 310 F.and 320 F. and passed through the bauxite bed at atmospheric pressureand between about 0.25 and about 1.0 volume of gas per volume of bauxiteper hour. At the end of about 1 hour the bauxite was found to have avolatile content of about 3%, which decreased only slightly afterpassing the vapors through the mass for 10 hours. To this catalyst massaluminum chloride was charged by passing the dried normal butane vapors,which had been previously treated with aluminum chloride to removetraces of olefins at a temperature of about 70-80 F., through a drumcontaining solid aluminum chloride at a temperature of between about 270F. and about 290 F. This admixture Was introduced into the bauxite massuntil the aluminum chloride was present in about 8% by weight, whichgave an active isomerization catalyst.

Example 2 The catalyst mass as produced in Example 1 was then maintainedat a temperature of about 300 F. and there was passed therethrough amixture of normal butane containing about 6% of anhydrous hydrogenchloride at a throughput of about 1 v./v./hr. The run was continued fora total of about 450 hours at a reaction temperature of about 300 F.while maintaining a pressure of about 200 pounds per square inch.Aluminum chloride was added intermittently with the feed stock so thatin so far as possible a substantially constant conversion wasmaintained, giving a product containing about 40% isobutane. Thecatalyst life as measured in gallons of isobutane per pound of aluminumchloride used amounted to about 1'70 for the optimum operation.

The above conditions as set forth varied somewhat, particularly as tothe amount of aluminum chloride introduced at various times during thecarrying out of the run, but the overall average closely approximatesthe figures herein stated.

Having thus fully described the character of the invention, what isdesired to be secured by Letters Patent is:

1. A process for the production of a catalyst mass useful in theisomerization of normal paraffins to isopar-aflins which consists ofdehydrating a bauxite containing more than 3 weight per cent of water bypassing anhydrous butane at between about 250 F. and about 350 F., underfrom about 0 to pounds per square inch gauge pressure, through thebauxite until the water content thereof is between about 1.5% and about3% by weight, followed by passing anhydrous butane under substantiallythe same temperature and pressure conditions in contact with aluminumchloride also maintained under substantially the same temperature andpressure conditions and passing the resultant vapor admixture throughthe said dehydrated bauxite mass whereby the aluminum chloride isimpregnated thereinto.

2. A process as in claim 1 wherein the butane employed is normal butane.

3. A process as in claim 1 wherein the butane is replaced by normalpentane.

4. A process as in claim 1 wherein the butane employed is normal butaneand the impregnation of the dehydrated bauxite with aluminum ch10-ride-normal butane vapors is continued until the catalyst mass containsbetween about 6% and about 40% by weight of aluminum chloride based onthe bauxite.

WALTER H. RUPP. CLARKE T. HARDING.

REFERENCES CITED The following references are of record in the file ofthis patent:

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